Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. For example, Spinal Cord Stimulation (SCS) techniques, which directly stimulate the spinal cord tissue of the patient, have long been accepted as a therapeutic modality for the treatment of chronic neuropathic pain syndromes, and the application of spinal cord stimulation has expanded to include additional applications, such as angina pectoralis, peripheral vascular disease, and incontinence, among others. Spinal cord stimulation is also a promising option for patients suffering from motor disorders, such as Parkinson's Disease, Dystonia and essential tremor.
An implantable SCS system typically includes one or more electrode-carrying stimulation leads, which are implanted at a stimulation site in proximity to the spinal cord tissue of the patient, and a neurostimulator implanted remotely from the stimulation site, but coupled either directly to the stimulation lead(s) or indirectly to the stimulation lead(s) via a lead extension. The neurostimulation system may further include a handheld patient programmer to remotely instruct the neurostimulator to generate electrical stimulation pulses in accordance with selected stimulation parameters. The handheld programmer may, itself, be programmed by a technician attending the patient, for example, by using a Clinician's Programmer (CP), which typically includes a general purpose computer, such as a laptop, with a programming software package installed thereon.
Thus, programmed electrical pulses can be delivered from the neurostimulator to the stimulation lead(s) to stimulate or activate a volume of the spinal cord tissue. In particular, electrical stimulation energy conveyed to the electrodes creates an electrical field, which, when strong enough, depolarizes (or “stimulates”) the neural fibers within the spinal cord beyond a threshold level, thereby inducing the firing of action potentials (APs) that propagate along the neural fibers to provide the desired efficacious therapy to the patient.
Many patients have disability from loss of motor function and control following stroke, depending upon the extent and location of the injury. After a stroke, the cortex can reorganize both spontaneously and with physical therapy such that the patient can regain motor function and control. That is, cortical tissue that survives the stroke can be re-mapped (e.g., spontaneously or through physical therapy) to provide motor control for body regions that were previously controlled by cortical tissue that did not survive the stroke.
Cerebellar stimulation has been shown to potentiate functional recovery over physical therapy alone, ostensibly by increasing cortical excitability to facilitate cortical tissue re-mapping, and improve the relearning process. However, cerebellar stimulation requires highly invasive, deep brain surgery, which can add morbidity to patients whose function is already compromised from stroke. Additionally, deep cerebellar stimulation is not likely easily reversible. If the stimulation system is needed only for a few months or years post-implant, removal of cerebellar electrodes may not be straightforward.
Thus, there remains a need for a minimally invasive, reversible system for increasing cortical excitability through cerebellar pathways in order to treat stroke patients.